PROJECT SUMMARY/ABSTRACT In this R01 application we propose to examine the efficacy of monthly financial incentives contingent on observed breastfeeding (BF), supplemental to existing support from the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) program and home-based individual BF support, among low- income mothers. Low-income racial/ethnic-minority women breastfeed for an average duration of four months despite evidence-based recommendations by the American Academy of Pediatrics to exclusively breastfeed for six months of life in addition to continued breastfeeding through the first year. Insufficient duration of any BF is related to multiple maternal and child health problems, and increases in BF duration could be cost saving medically and societally. Though peer support has been effective in prolonging BF duration, the effect has not been as strong for WIC-eligible, low-income mothers. An incentive-based intervention was tested among low- income Puerto Rican mothers in a pilot study (R03HD077057) resulting in promising outcomes of monthly financial incentives contingent on observed BF for 6 months combined with WIC BF usual care, compared to WIC BF usual care only (BF rates: 89% vs. 44% at 1-month; p = 0.01; 89% vs. 17% at 3-month; p<0.01; 72% vs. 0% at 6-month; p<0.01; N = 36). We propose a 2-group parallel randomized controlled trial in which half of the 168 WIC-eligible mothers will be allocated into each of the two study groups: (1) Standard Care BF Support (WIC support + home-based individual support; Standard Care (SC)) and (2) Incentives contingent on demonstrating successful BF (SC + Breastfeeding Incentives; SC+BFI). Participants randomized into SC will receive standard breastfeeding services from WIC and home visitations for individual support and problem- solving. Participants randomized into SC+BFI will receive the same services as Control except that monthly financial incentives are contingent on observed BF and delivered at the end of each month. The study will be conducted in two regional sites with high concentrations of low-income racial/ethnic minority mothers, Philadelphia, PA and Wilmington, DE. The primary outcome will be the BF rate for 6-month postpartum, the exploratory outcome will be the BF rate at 12-month postpartum, and the secondary outcomes will be infant outcomes (i.e., weight gain and emergency room visits). We hypothesize that SC+BFI will increase the BF rate by 25% at 6-month postpartum and have significantly lower infant weight gain and incidents of ER visits for infants at 3-month postpartum, compared to SC. We will track the costs of intervention, formula purchased by mothers, and infant medical care in both groups. We will also conduct interviews with corporate representatives and insurance companies to explore community- and policy-level support to sustain the incentive-based intervention for WIC mothers. The aims of the proposal are guided by the mission of NICHD's Pregnancy and Perinatology Branch to improve the long-term maternal and infant health of low-income populations via encouraging breastfeeding in the translational research context.